北京地区大气环流型及气候特征

Atmospheric Circulation Types and Their Climatic Characteristics over Beijing

以北京地区为研究对象,应用Lamb-Jenkinson大气环流分型方法对1948—2008年的逐日平均海平面气压场进行定量计算环流指数。通过对27类逐日环流分型结果的统计分析得出:北京地区主导环流类型依次为A型、C型和SW型,其频率分别为23.8%、15.4%和7.0%;A和C环流型频率均呈逐年上升趋势,但A型频率上升速度远大于C型;春季北京主导环流类型为A型和C型,夏季主导环流型为C型和SW型,夏季CSW型环流所占比例也较大,秋季和冬季为A型。通过主导环流型和北京气温、降水之间变化规律的分析可知:冬季在A型环流的控制下北京地区多为低温晴好天气;夏季在C型环流的控制下北京地区降水增多,在SW型环流的控制下北京地区降水偏少,而CSW型环流控制下北京地区呈现干热天气状态,2000年后尤为明显。

Lamb-Jenkinson atmospheric circulation classification scheme was used to classify the circulation type of daily average sea level pressure over Beijing in 1948-2008. The following conclusions are drawn that among 27 circulation types,primary types are A,C and SW,and their occurrence frequencies are 23.8%,15.4% and 7.0%,respectively. Frequencies of types A and C tend to increase,but the increasing rate of type A is much greater than that of type C. The seasonal primary circulation types are A and C in spring,C and SW in summer,and A in autumn and winter,but type CSW can not be ignored in summer. It is fine and cool in winter Beijing under type A,mostly rainy in summer under type C and rainless under type SW,and dry and hot under type CSW,especially after 2000.